José J Duconge

Preparation of hollow magnetite microspheres and their applications as drugs carriers

AbstractHollow magnetite microspheres have been synthesized by a simple process through a template-free hydrothermal approach. Hollow microspheres were surface modified by coating with a silica nanolayer. Pristine and modified hollow microparticles were characterized by field-emission electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, FT-IR and Raman spectroscopy, and VSM magnetometry. The potential application of the modified hollow magnetite microspheres as a drug carrier was evaluated by using Rhodamine B and methotrexate as model drugs. The loading and release kinetics of both molecules showed a clear pH and temperature dependent profile.Graphical abstractHollow magnetite microspheres have been synthesized. Load-release experiments with Rhodamine-B as a model drug and with Methotrexate (chemotherapy drug used in treating certain types of cancer) demonstrated the potential applications of these nanostructures in biomedical applications.

Synthesis and Characterization of Zeolite Based Porous Ceramic Membranes

Abstract New porous zeolite based membranes were synthesized using a ceramic methodology and characterized by means of XRD, SEM, EDAX and permeation tests. The membranes were produced by thermal transformation of natural clinoptilolite. The XRD study showed clinoptilolite amorphization at 600–900°C. A posterior recrystallization to a siliceous phase and a compact aluminosilicate phase at 900–1150°C was also produced. The Permeability [B] and Permeance [Π] of H2 and CO2 were measured using the Darcy Law correlation. It was also applied for gaseous laminar flow using the Carman‐Kozeny equation. With the help of this equation the membrane pores sizes were measured. It was shown that the membrane porosity can be controlled by the grain size of the original natural zeolite powder. The membranes were further transformed by hydrothermal synthesis to obtain materials covered with an AlPO4‐5 molecular sieve. In conclusion, novel, inexpensive, strong, high permeation rate, and high temperature membranes were produced with natural clinoptilolite, a low cost and available material.

Degradation of phenol by mechanical activation of a rutile catalyst

In the present paper a novel mechanochemical process for the elimination of organic pollutants dissolved in water is proposed. In this regard, phenol aqueous solutions (100mgL(-1)) were ball-milled for 0, 12, 18, 24, 36, 48, and 72h with and without a well-characterized (XRD, SEM, and N(2) Adsorption), rutile powder catalyst and the reaction products analyzed with UV and GC/MS. It was found that when the catalyst was not included in the process, phenol was not affected, but when it was included, phenol was decomposed. The catalyst itself did not change and the reaction follows a pseudo-first-order kinetics. Besides, intermediates which are characteristic of the ()OH radical mechanism were found in the reaction products. Then, a mechanism similar to those accepted for other advanced oxidation processes was proposed. The value measured for the pseudo-first-order reaction constant was very low, indicating that the reported process is inefficient. Nevertheless, this problem could be solved by applying catalysts consisting of particles with smaller diameters.